If you look closely at the top right corner of the instruction sheet you will notice that there were 2 ounces of hops with the kit, a 1 oz package for bittering and a 1 oz package for aroma and if you look real closely you would notice that they use the same variety of hop for both so you simply can't use them in the wrong order. Here's a link to the instructions in case you misplaced yours.

My brother in law did a Brewer's Best kit that was similar, but the same varietal doesn't necessarily mean they're the same. It was an IPA, with Columbus and Cascade for bittering and Cascade for aroma. The two Cascade packs were the same size, and varietal. But the AA ratings were different (the bittering Cascade were slightly higher).

So they might not have been identical, but couldn't have been that far off. In either case, the differences for the OP's beer should be minimal at the most. And without a side by side tasting, might not ever be able to notice.

How much headspace can I leave in the secondary carboy? It's 5 gallons now once racked it will be a little less. I have a 5 gallon carboy but I think they are actually 5.5 so there will be a bunch of room at the top. With wine, you have to fill it to an inch below airlock.

How much headspace can I leave in the secondary carboy? It's 5 gallons now once racked it will be a little less. I have a 5 gallon carboy but I think they are actually 5.5 so there will be a bunch of room at the top. With wine, you have to fill it to an inch below airlock.

No worries. I've done 5 and 6 gallon batches, headspace anywhere from a couple to maybe 5 inches. The idea is to transfer before fermentation is completely finished, that way when you transfer and attach the air-lock there is still some fermentation happening to purge the head-space air. That being said, I've often transferred too late for this and never once had a problem. Just make sure everything is cleaned and sanitized well